The present invention relates generally to systems and devices for managing content data, and more particularly to systems and devices for processing the protocols that relate to transfer of the control information defined to use encrypted content data.
Even more specifically, the invention relates to a management system for content data handling which includes protocol processing for transfer of control information inclusive of the key data defined to use the content data handled in a recorder/player and a storage device. The invention also relates to a recorder/player and storage device in the system.
When content data such as musical data or image data has a copyright, there is risk of the copyright holder's rights being infringed unless appropriate measures for copyright protection are taken. However, if top priority is assigned to copyright protection and the circulation of the content data is impeded, this will turn out to be disadvantageous to the copyright holder who can collect copyright royalties for copies of the copyrighted material.
Content data whose copyright is to be protected is delivered mainly via a digital communications network, broadcasting waves, or the like. When a user uses such data, the user usually records the data onto some kind of storage medium before starting reproduction with a reproducing device. Currently, magnetic disk drives are known as control-featured storage devices large in capacity and high in access performance. A large majority of magnetic disk drives are fixedly built into recorder/players, and such a magnetic disk drive is unknown that allows internal data to be used in other reproducing devices. In terms of operational convenience, however, the use of portable types of storage devices is likely to grow in the future. Under these circumstances, memory cards are known as the portable types of storage devices that, although lower than magnetic disk drives in capacity, have a copyright protecting function.
Such data is reproduced using the recorder/player that was used to receive the delivered data, or a portal type of dedicated device for reproduction.
To protect the copyright for the data which was recorded in a portable type of storage device connectible to a recorder/player, it is important to provide both the recorder/player and the storage device with some security measure in order to prevent the recorded data from being reproduced overstepping the range of the conditions on which the copyright holder insists. Providing devices with security protection requires that for data exchange in a region freely accessible from the inside and outside of the devices, free data access in plain text should be prevented by, for example, conducting authentication processes between the devices that are to exchange data, or encrypting the data itself. At the same time, however, as these authentication or encryption processes become more stringent, the processes required from the time the user issues a data usage request, until data has actually been made available to the user, will increase and a situation under which the data cannot be reproduced smoothly is likely to result.
Patent References 1 (WO01/013358) and 2 (WO01/043339), for example, propose techniques in which a copyright relating to the digital data to be used is protected by encrypting the data and, at the same time, preventing unauthorized acquisition, falsification, etc. of a key for decrypting the encrypted data, and of the usage terms and conditions of the encrypted data. Also, Patent Reference 3 (Japanese Patent Laid-open No. 2004-302701) discloses a technique relating to a storage device in which the plurality of encryption and input/output processes sent from a host device will be split into a plurality of procedures and then concurrently performed so that the tampering resistance of the data to be kept private between the storage device and a host device will improve when the data is input and output in encrypted form.